Forum Discussion
Brett_10751
Nimbostratus
Nimbostratusirule to change to downpage pool and change persistence
I have a VIP setup that has POOL_A with two nodes in it with default persistence profile - source address affinity with a value of 600 seconds.
On the VIP I have a irule setup that if it sees that the VIP is down then it will fail over to POOL_B without persistence. Pool B is a downpage that we wanted to use if the site exceeds its connection limits or is down for maintenance.
when LB_FAILED { persist none LB::reselect pool POOL_B }
So as a test I set each node in POOL_A to have a connection limit of 1. So after I initiated a second connection to either node in POOL_A I was sent over to POOL_B's downpage, but then I changed the connection limit back to unlimited on POOL_A and the pool was available but my client persisted on the downpage pool - POOL_B. After 10 minutes (600 seconds) after refreshing I was eventually redirected to POOL_A
Not sure what I persisted on the downpage even though POOL A was available
Shouldn't this work? Any ideas on how I can do this differently?
Thank you,
Brett
5 Replies
- The_BhattmanHi Brett,
Instead of refreshing did you close the application or browser and then restarted it?
Also you can use 'persist delete' to remove a persistence entry from within the iRule instead of setting it to none:
persist
http://devcentral.f5.com/wiki/default.aspx/iRules/persist
I hope this helps
Bhattman 
ArieAltostratus
Aside from the persistence issue (and without knowing the architecture), will POOL_B always be available when POOL_A is not?Unless you need a lot of functionality on the "downpage" it may be preferable to embed the HTML on the LTM and send it via a "respond"-command when POOL_A is down. That way you can display the page even if the entire environment behind the LTMs is down.
- nitass
Employee
it seems to be okay to me.
[root@orchid:Active] config b virtual bar list
virtual bar {
snat automap
pool foo1
destination 172.28.17.88:http
ip protocol tcp
rules myrule
persist source_addr
}
[root@orchid:Active] config b rule myrule list
rule myrule {
when LB_FAILED {
persist none
LB::reselect pool foo2
}
}
[root@orchid:Active] config b pool list
pool foo1 {
members 10.10.70.110:http {
limit 1
}
}
pool foo2 {
members 65.55.17.26:http {}
}
curl -I http://172.28.17.88/ <<<<< 1st request got response from foo1
HTTP/1.1 200 OK
Date: Fri, 10 Jun 2011 19:50:30 GMT
Server: Apache/2.0.59 (rPath)
Last-Modified: Sun, 24 Oct 2010 20:57:08 GMT
ETag: "65c0-123-1e67b100"
Accept-Ranges: bytes
Content-Length: 291
Vary: Accept-Encoding
Content-Type: text/html; charset=UTF-8
curl -I http://172.28.17.88/ <<<<< 2nd request got response from foo2
HTTP/1.1 200 OK
Date: Sat, 11 Jun 2011 04:56:09 GMT
Server: Microsoft-IIS/6.0
P3P:CP="BUS CUR CONo FIN IVDo ONL OUR PHY SAMo TELo"
S: CO1MPPRENA19
X-Powered-By: ASP.NET
X-AspNet-Version: 2.0.50727
Pragma: no-cache
Set-Cookie: MC1=V=3&GUID=743c5453cf264ce69fc7072de5853936; domain=.17.88; expire s=Mon, 04-Oct-2021 19:00:00 GMT; path=/
Cache-Control: no-cache
Content-Type: text/html; charset=utf-8
Content-Length: 6293
curl -I http://172.28.17.88/ <<<<< 3rd request got response from foo1
HTTP/1.1 200 OK
Date: Fri, 10 Jun 2011 19:50:39 GMT
Server: Apache/2.0.59 (rPath)
Last-Modified: Sun, 24 Oct 2010 20:57:08 GMT
ETag: "65c0-123-1e67b100"
Accept-Ranges: bytes
Content-Length: 291
Vary: Accept-Encoding
Content-Type: text/html; charset=UTF-8
there is no foo2 in persistence table.
[root@orchid:Active] config b persist show all
PERSISTENT CONNECTIONS
| Mode source addr Value 172.28.17.80
| virtual 172.28.17.88:http node 10.10.70.110:http age 53sec
| Mode source addr Value 192.168.206.96
| virtual 172.28.17.88:http node 10.10.70.110:http age 1sec 
Brett_10751I was able to test this further on a development vip/pools using examples provided by nitass and persistence does not seem to be an issue. It is working as it is suppose to. I didn't try bhattman's suggestion as it seemed to be working okay with persist none on the test VIP. I'll have to test this further on my actual production VIP which happens to be HTTPS which I failed to mention in the intial post.
I also tried Arie's suggestion of doing a HTTP respond and it works well as long as it is an http vip with a http profile attached. I really like the idea of doing it this way, but is it possible if you have an HTTPS VIP passing traffic to HTTPS nodes, F5 NOT terminating the SSL connection?
Thanks for all the help
Brett- hoolio
Cirrostratus
Hi Brett,
If you import the SSL cert and key you can selectively enable decryption on the request if the pool is down:
http://devcentral.f5.com/wiki/default.aspx/iRules/HTTPS_passthrough_fallback_URL.html
I don't think you could do this outside of CLIENT_ACCEPTED though.
Aaron
